US3652553A - Process for the production of caprolactam - Google Patents

Process for the production of caprolactam Download PDF

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Publication number
US3652553A
US3652553A US883269A US3652553DA US3652553A US 3652553 A US3652553 A US 3652553A US 883269 A US883269 A US 883269A US 3652553D A US3652553D A US 3652553DA US 3652553 A US3652553 A US 3652553A
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United States
Prior art keywords
catalyst
boron oxide
oxime
steam
over
Prior art date
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Expired - Lifetime
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US883269A
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English (en)
Inventor
Manfred Mansmann
Otto Immel
Hans Zirngibl
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Bayer AG
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Bayer AG
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Filing date
Publication date
Priority claimed from DE19681814489 external-priority patent/DE1814489C3/de
Application filed by Bayer AG filed Critical Bayer AG
Application granted granted Critical
Publication of US3652553A publication Critical patent/US3652553A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
    • C07D201/02—Preparation of lactams
    • C07D201/04—Preparation of lactams from or via oximes by Beckmann rearrangement

Definitions

  • This invention relates to an improvement in the process for the production of lactams by catalytically rearranging cyclic ketoximes in the gas phase at a temperature of from 200 to 400 C. in the presence of a particular modification of boron trioxide.
  • cyclic ketoximes can be rearranged into the corresponding lactams in the gas phase at 200 to 400 C. on solid catalysts.
  • Catalysts comprising boric acid or boron oxide on supports have proved to be particularly effective.
  • Proposed supporting materials include aluminium oxide, silica gel, diatom-aceous earth, active carbon, titanium dioxide, stannic oxide and alkaline earth metal phosphates and sulphates.
  • the oxime vapours are passed over these catalysts, with or without inert carrier gases, at elevated temperature and at normal, elevated or reduced pressure.
  • water containing oxime may be used for the rearrangement reaction, or the evaporated oxime and steam as a carrier gas may be, passed over the catalyst. The presence of steam considerably increases the rearrangement activity of the catalysts.
  • the B 0 losses can be replenished at regular intervals, especially during the reactivation treatment required to burn oif carbon-containing deposits from the catalyst, by pyrolising an orthoboric acid alkyl ester.
  • the boron oxide is reactivated in a special process stage in which the boric acid ester is delivered to the catalyst fluidised by means of an inert gas at a temperature of from 200 to 800 C. The alcohol component of the ester is converted into cracking products of no further value.
  • This object is accomplished by the improvement which comprises passing said steam over the X-ray crystalline modification of boron oxide at a temperature of from 200 to 450 C. before passing over said catalyst.
  • the catalyst may be used either in the form of a fixed bed or in the form of a fluidised bed.
  • the temperature of the crystalline boron oxide may be equal to or even above or below the temperature of the catalyst.
  • the process may be carried out at atmospheric pressure and at elevated or reduced pressure.
  • vitreous boron oxide slowly softens at temperatures as low as from 250 C. upwards and, at 270 C., is largely molten in form. Consequently, vitreous B 0 is not really suitable for saturating the gas stream in commercial operation because vessels of excessively large dimensions would have to be used in order to obtain an adequately large B 0 surface.
  • boron oxide from melting by using an inert supporting material, this would in principle necessitate the preparation of a special catalyst, which is the very thing it is desired to avoid because the price of the catalysts in question is governed less by the costs of the raw materials than by production costs.
  • the use of boron oxide on a support would be complicated in commercial operation by virtue of the fact that the supporting material would be left behind following volatilisation of the boron oxide and have to be removed before the next run.
  • the process according to the invention employs the X-ray crystalline modification of boron oxide, which does not have any of the disadvantages referred to above because its melting point is in the range from 450 to 470 C., and because there is no evidence of softening or sintering below the melting point.
  • volatilised crystalline boron oxide does not leave any residue so that the volatilised component can be replenished simply by adding fresh crystalline boron oxide.
  • the steam required for the rearrangement reaction can readily be saturated with boric acid in the usual way.
  • a saturation tower heated to the required temperature may be filled with pieces of crystalline B 0 and the stream of steam or of the mixture of oxime vapour and steam may be passed through. Saturation may alternatively be carried out on the fluidised bed principle.
  • an inert gas for example nitrogen or carbon dioxide
  • the quantity of steam is not especially critical and may be varied within wide limits, although the preferred steam component, based on the oxime used, amounts to from 1 to 30% by weight.
  • the X-ray crystalline modification of B is known. X-ray crystalline B 0 can be obtained from H BO in accordance with the procedure described in Handbuch der Prtiparativen Anorgischen Chemie, published by G. Brauer, second edition, Stuttgart 1960, page 699. Once X-ray crystalline B 0 is available, further preparation may be carried out very easily by innoculating an H BO melt at 22-5 to 250 C.
  • the steam is passed over the X-ray crystalline modification of boron oxide at a temperature of from 200 to 450 C., after which the steam is mixed with the oxime vapour at a temperature around the rearrangement temperature and the vapour mixture is subsequently brought into contact with the catalyst.
  • Both the steam and the oxime vapour may be mixed with an inert gas, for example nitrogen or carbon dioxide.
  • the oxime vapour introduced before the catalyst zone may be substantially free from water.
  • the temperature of the crystalline boron oxide in the saturator is kept between 200 and 400 C. and is substantially equal to that of the catalyst.
  • the temperature of the crystalline boron oxide can be so far above the temperature of the catalyst that the quantity of boron oxide transported by the oxime-free steam-containing gas stream corresponds to that which can be transported following admixture with the oxime vapour containing small quantities of steam at the temperature of the catalyst.
  • the temperature is limited by the melting temperaure of the crystalline B 0 (450 C.).
  • the steam is passed, together with the oxime vapour, optionally in admixture with inert gas, rather than on its own, over X-ray crystalline boron oxide and then over the catalyst.
  • precautions need only be taken to ensure that substantially the same temperatures prevail both in the catalyst layer and the boron oxide layer.
  • the crystalline boron oxide should lose some of its activity as a result of the deposition on it of carbonaceous products, these carbonaceous products may be removed by burning off. However, they must be burnt off at temperatures below the melting point of the crystalline boron oxide.
  • One suitable method comprises gradually burning off the carbonaceous products with oxides of nitrogen. If combustion is carried out in a fluidised bed, nitric acid may be sprayed on to the fluidised B 0 particles which have a temperature of from 150 to 450 C., in which instance too high a temperature, and hence fusion of the B 0 can readily be prevented because of the evaporating drops of liquid.
  • the preferred temperature of rearrangement is from 250 to 360 C.
  • EXAMPLE 1 (a) Without a saturator 245.6 g. of cyclohexanone oxime and 50.0 g. of water were passed for 12 hours at 40 torr over 30 g. of catalyst fixedly arranged in a tubular furnace, which consisted of 12.9% by weight of B 0 on titanium dioxide as the support, and which had been heated to 340 C. Subsequently, quantitative determination of the B 0 content of the catalyst revealed a value of 8.3% by weight.
  • EXAMPLE 2 (a) Without a saturator 376.6 g. of cyclohexanone oxime and 76.3 g. of water, in the form of steam, were passed in a period of 18 hours over 30 g. of a catalyst consisting of 12.9% by weight of B 0 on titanium dioxide, at 40 torr/ 340 C. The catalyst then had deposits of carbon removed from it by heating for 1 hour at 700 C. in air, after which it was reused for rearrangement. Another 132.1 g. of oxime and 25.0 g. of water were passed in vapour form over the catalyst in a period of 5 hours, during which the activity of the catalyst fell to such an extent that the test had to be terminated. Quantitive determination of the B 0 content of the catalyst revealed a value of only 2.2% by weight.
  • EXAMPLE 4 A layer of 10 g. of catalyst and another layer of 40 g. of crystalline boron oxide were arranged in a reaction tube 2 cm. wide in such a way that the two layers were only separated from one another by a screen.
  • the catalyst consisted of 18% by weight of boron oxide on titanium dioxide as the supporting material, and had a grain size of from 0.6 to 1 mm.
  • the crystalline boron oxide preceding the catalyst layer had a grain size of from 1 to 5 mm.
  • the gas mixture of cyclohexanone oxime vapour (22 g./hour), steam (2.3 g./hour) and nitrogen (50 l./hour) was initially passed through the boron oxide layer and then through the catalyst layer, both layers being kept at 320 to 350 C.
  • the catalyst on which the oxime was rearranged was regenerated at intervals of 12 hours by heating at 600 to 700 C. in air.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US883269A 1968-12-13 1969-12-08 Process for the production of caprolactam Expired - Lifetime US3652553A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19681814489 DE1814489C3 (de) 1968-12-13 Verfahren zur Herstellung von Lactamen

Publications (1)

Publication Number Publication Date
US3652553A true US3652553A (en) 1972-03-28

Family

ID=5716135

Family Applications (1)

Application Number Title Priority Date Filing Date
US883269A Expired - Lifetime US3652553A (en) 1968-12-13 1969-12-08 Process for the production of caprolactam

Country Status (5)

Country Link
US (1) US3652553A (enrdf_load_stackoverflow)
BE (1) BE743044A (enrdf_load_stackoverflow)
FR (1) FR2026130A1 (enrdf_load_stackoverflow)
GB (1) GB1233500A (enrdf_load_stackoverflow)
NL (1) NL6918694A (enrdf_load_stackoverflow)

Also Published As

Publication number Publication date
DE1814489A1 (de) 1970-06-25
NL6918694A (enrdf_load_stackoverflow) 1970-06-16
DE1814489B2 (de) 1976-12-23
BE743044A (enrdf_load_stackoverflow) 1970-05-14
FR2026130A1 (enrdf_load_stackoverflow) 1970-09-11
GB1233500A (enrdf_load_stackoverflow) 1971-05-26

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